Chatwin and Rossum spoke to a group of reporters in a press conference last week in Beverly Hills, Calif., about the movie, which opens this Friday. The following Q&A features edited excerpts of that interview.

Justin, how cool was it fighting Chow Yun-Fat, who played Master Roshi?

Chatwin: It felt good. It felt really good. Fighting with him was great, because he's a pro at this, and I was a fan of the John Woo movies like Hard-Boiled. I remember the first day when I saw him doing his Master Roshi. In the process of auditioning for this, I remember reading with other Master Roshis, and people were playing the part small because he was a feeble old man.

I remember when Chow came in, and he just did this huge [campy performance]. I was like, "Oh, my God, he's overacting. This is crazy! What is he doing?" And then as he kept on doing it day after day after day, I was like, "Oh, my God, there's something I didn't see in the manga, which is the broad comedy, almost like kabuki theater that manga has to have that makes it different from movies like Iron Man and Batman." It's this broad comedy, almost Stephen Chow-ish, that Chow really understood. I really think it rubbed off on us, because we started getting goofier and goofier, almost like Three Stooge-y, because of what Chow brought to the film. He was really a great influence on us.

Why do you think so many people are attracted to Dragon Ball?

Chatwin: I went to the manga museum when I was in Kyoto. They had a library, and it was like three floors, like a giant Natural History Museum-sized building full of manga. There are so many different kinds of manga out there. I asked myself that same question. Why is Dragon Ball so big and there are all these other ones out there that haven't become popular?

I think it comes down to the story. It's the values. These stories are like these Greek epics. They're about virtue and honor and fighting evil and becoming a man and serving your country and serving a greater cause. For me, what's important is to carry on those stories and evolve it from the Monkey King, which Dragon Ball was based off of, and keep those stories alive, because if we don't adapt them, they'll just drift away.

James Marsters is Lord Piccolo

Were you already Dragon Ball fans?

Rossum: Well, I loved the manga because it was a little more R-rated, and I thought that the relationship between Bulma and Roshi always was very funny. I really enjoyed that in my studies of her. I think we kind of took everything we could from the manga and understand that some things are going to be changed, but just by virtue of the fact that you're a live actor playing it live action, it can't be exactly like the manga. But you try and bring the spirit and the energy to the characters and the backstory that you learn from the manga and bring it to this story, which is really an introduction of those characters. And then don't do it naked.

Chatwin: I think I was like 18 when I watched it. When I watched it, I was like, "Wow, this is crazy. I really like this." But it wasn't until I got the part that I actually sat down with Dragon Ball and Dragon Ball Z and Dragon Ball GT and actually started studying the character. That was the first thing I did. I was like, "I've got to understand this character and understand the qualities, understand all the episodes and the family tree and all that. Then I have to get rid of all those ideas and bring those qualities out of Justin." I didn't want to play an idea of the character, because that, I think, would have been the biggest pitfall of the movie, actors playing ideas of what these characters are, as opposed to genuinely bringing forth qualities of themselves.

OK, so how did you learn to fight?

Rossum: This completely kicked my ass. I had never done anything like this before. I grew up loving Jean-Claude Van Damme movies, it's kind of a little bit embarrassing to say. Just anything with him is awesome, and I've always kind of wanted to do a film like that. I always wanted to play a kind of tougher, more independent woman kind of character, and this was the perfect opportunity to shoot three guns, learn how to ride a motorcycle and dye part of my hair blue.

So in addition to the training we all did as a team, which was pretty rigorous, I think, thinking back on it, I can only imagine it's kind of like how women describe childbirth. Hold on, let me go, I'm going somewhere with this, I just thought of this over lunch. Like, it's really awful when you're doing it, and like two years later, you're like, "Oh, it was amazing, it's great." But when you're in it, it's awful. But also fun, because we're doing it as a team, and it's like group childbirth.

Chatwin: We did that for five weeks, and then we continued it when we got down to Mexico, and we needed it, too, because the elevation was so high. So when we were fighting, especially in that party scene, I remember I had to get a shot. They had to give me a shot in the ass, a cortisone shot, because my lungs couldn't take the altitude. So we needed to be, A, in shape, and B, we needed more oxygen in our lungs, because we were used to the sea level here.

Was it challenging making a movie that fans of Dragon Ball, as well as those not familiar with it, would appreciate?

Chatwin: The original fans are like 20 or 30 years old. There's a whole generation of 6- to 18-year-olds that Dragon Ball wasn't introduced to because they have Batman and they have all these other cartoons. This is for the new generation, people that have no idea, to get more involved with Dragon Ball and also for the fans. I hope they like it.